1. Field of the Invention
The subject invention is related to tandem duplicating systems for advancing copy sheets through two printing stations to generate two-sided copy, and is specifically directed to the reversing transport means thereof for conveying the copy sheets from the first printing station to the second printing station of the duplicating system.
2. Description of the Prior Art
There are various constructions of tandem duplicating systems having transport means for conveying copy paper from a first printing station to a second printing station for both dual pass printing and two-sided printing. One example of a prior art system is the Model 350-T duplicating system of A. B. Dick Company, Chicago, Illinois, the assignee of the present invention. This prior art system is depicted in FIGS. 1 and 2 of the drawings.
The tandem duplicators of the prior art transfer copy sheets from the first duplicating machine to the second duplicating machine by securing the sheet on a conveyor via tracking and gripping rollers, often resulting in ink-tracking and ink-smearing because the rollers engage that side of the sheet which is printed at the first machine, pick up ink and transfer it to other areas of the copy sheet. Various configurations of tandem duplicating systems of this type are disclosed in U.S. Pat. Nos. 2,625,101; 3,829,084; 3,944,218 and 4,015,522.
It is also known to utilize vacuum conveyor belts for transferring documents between remote stations, see for example, U.S. Pat. Nos. 3,889,801 and 4,047,812.
None of the known systems deals with or is directed to solving the problem of ink tracking during two-sided or dual pass duplicating.